Remember autoreturn setting

Create a new variable "_VimTmuxCmdAutoreturn" which remembers the value
of the autoreturn parameter used by the last invocation of
VimuxRunCommand or RunVimTmuxCommand. Use this parameter in the
VimuxRunLastCommand function.
Merge pull request #37 from abstiles/patch-autoreturn

Remember autoreturn setting
Allow multi-word session and window names. Fixes #34
Note ideal tmux version in README
Adds information about vim-vroom
Merge pull request #40 from alindeman/patch-1

Adds information about vim-vroom
Escape $ before sending commands to tmux. Fixes #39
Add vimux-nose-test link to README.
add VimuxPromptString
updated from benmills remote master
Merge pull request #49 from jtmkrueger/master

Allow for Customization of prompt string
Moved default outside if statement.
Merge pull request #50 from brianjriddle/master

Fixed for VimuxRunPrompt not working with default
Focus runner pane when inspecting.
Improve close_runner_pane

Do not execute `tmux kill-pane` when a runner pane is not available

Avoids UI glitches when :VimuxCloseRunner is auto-called before exiting
Vim.
Merge pull request #56 from tonyskn/betterCloseRunnerPane

Improve close_runner_pane
Add vimux-golang to README
Fixed typo in doc/vimux.txt
Merge pull request #59 from chip/master

Fixed typo in doc/vimux.txt
fix variable scopes